Body odor may be generated in the area under the arms due to a high concentration of sweat glands. While perspiration is odorless, it contains natural oils that can be nutrient source for bacteria living on the skin. These bacteria interact with the natural oils, converting them into odor producing compounds. Antiperspirant compositions contain an active, such as an aluminum salt, that reacts with the electrolytes in perspiration to form a plug in the ducts of sweat glands. The plugs prevent perspiration from exiting the duct, thereby depriving the bacteria of water and a food source. Antiperspirant compositions may be applied to the skin in either a contact type product form, e.g., a stick or roll-on, or non-contact type product form, such as an aerosol spray. Aerosol spray devices that dispense an antiperspirant composition are known in the art. Various examples are described in U.S. Pat. No. 4,152,416; U.S. Pat. No. 4,806,338; U.S. Pat. No. 4,840,786; U.S. Pat. No. 4,904,463; U.S. Pat. No. 4,935,224; U.S. Pat. No. 5,298,236; U.S. Pat. No. 5,605,682; U.S. Pat. No. 5,814,309; U.S. Pat. No. 7,815,899; EP 674,899; WO 96/04884; WO 2004/014330; and WO 2007/001842.
Many aerosol antiperspirant users desire a product that minimizes the appearance of residue on the skin, has a dry rather than wet feel, has rapid perceived drying, is not sticky, and provides a cool/fresh feeling at time of application. Other desired product attributes include providing long lasting wetness and/or odor protection, an easily portable form for purses or small bags (as some users may apply the antiperspirant composition more than once a day) and minimizing the gassy cloud that forms during dispensing. While the relative importance/desirability of these characteristics may vary by geographical region and gender and not all users desire all or the same set of characteristics, a generally universal desire among aerosol antiperspirant users appears to exist for a dry rather than wet feel, minimizing the appearance of residue, and/or providing long lasting wetness/odor protection or efficacy.
While some currently marketed aerosol spray devices may provide at least some of these characteristics to varying degrees, there are often tradeoffs involved. For example, many currently available aerosol antiperspirant compositions also incorporate a volatile liquid (e.g., cyclopentasiloxane) as a carrier for the antiperspirant active. The volatile liquid evaporates following application to the skin, resulting in a dry skin feel, but sometimes leaves behind a visible residue (the antiperspirant active) that is subject to flaking and/or transfer to clothing. Flaking (or transfer) of the antiperspirant active may also reduce antiperspirant efficacy. Further in some cases the cyclopentasiloxane may not be deposited well by products containing propellant levels between 75% and 90%, which may further exacerbate the amount of visible residue and flaking mentioned above. Therefore, there is continuing desire to provide improved aerosol antiperspirant compositions and products.